clear

use "C:\Local\数据\Table 3\disance+population+GDP+document.dta" 

sum tradepro,detail

sum SurveyData,detail

sum document,detail

drop if tradepro ==.

gen d1 = 1 if tradepro != SurveyData

/// 93 obs when d1 = 1, 93/151 = 61.6%

gen d2 = 1 if tradeproc != document

/// 109 obs when d2 = 1, 109/151 = 72.2%

gen d3 = 1 if SurveyData != document

/// 129 obs when d3 = 1, 129/151 = 85.4%
